On Sun, 19 Sep 2004 21:17:25 -0000, Phil <
phil1960us@...> wrote:
> I've used up my Ammonium Perchlorate so I got HCl and H2O2. I
> understand that I need to use a bubbler to regenerate the etchant and
> have seen references to letting it run a long time. How long should I
> expect - hours? days?
>
You need no bubbler with H2O2.
The H2O2 is the "quick" version to get the oxygen in.
The slow and nasty fumes version is to keep it bubbling for hours,
then it takes the oxygen from the air.
So you see, no bubbler required. You can keep it and see if it speeds up
etching because of the agitation.
> Currently, my bubbler is a piece of vinyl tubing that I drilled #70
> holes in, This produces somewhat large bubbles. I'll try it but do
> those of you that use CuCl recommend something different, like an
> aquarium airstone?
As said if you use H2O2 for regeneration it isn't needed.
The big bubbles will be fine for agitation though.
>
> I'll be using about 3 Liters and doing a number of double sided boards
> in the 10x15 CM size range, 1 oz copper. I have an aquarium heater
> that will bring the temp up to about 100F (about 38C) if that matters.
NO DO NOT USE A HEATER!!!!!
The boiling point of HCl is VERY low, and even below the fumes increase
dramatically with heat. I experimented with that and don't want to repeat
the experience. Use a bubbler or mecanical movement/oscillation of the
board.
I'm still wondering if high frequency vibrations or even ultrasonic would
be a
good idea.
Quick guide for getting started:
Dilute the HCl to 10% or so. Put the board in and add a small amount of
H2O2.
You should see a reaction on the board and the etchant coloring slowly.
tiny bubbles are ok, but bigger, fast rising bubbles indicate too much
H2O2.
You must avoid that condition.
The H2O2 needs replenishing when the etchant turns from bright green to
dark green.
The HCl will need replenishing when you see blue "sludge" on the board and
the
etchant also gets slightly bluish. It is better to measure the HCl
molarity than
just using the blue sludge as a sign. see links section for a simple mehod
using two eyedroppers.
At the beginning you will need H2O2 each time. After enough boards there
is enough copper in to etch with CuCl only. Then you only regenerate with
H2O2
when the color turns. (note: H2O2 is lost if there is nothing to
regenerate left,
so don't add too much).
If you observe the things described it is a very good and cheap etchant.
Possible problems:
resist attacked (especially touch-up markers): reduce HCl, measure molarity
long etch times: not enough Cu solved yet, not enough H2O2.
etching stops suddenly but etchant is bright green, H2O2 doesn't do
anything:
HCl used up completely, add some, see the blue sludge on the board.
I hope i covered the most important things.
I really should write that up some day....
ST
P.S.: We MUST RESEARCH effects of vibrating the board and using ultrasonic
sound.
Could please someone use a ultrasonic cleaner (with water) and see if the
toner
comes off?